First of all, the space object could crash with another satellite like that time two space vehicles collided over Siberia in 2009. That accident had minor effects — the debris didn't cause much harm, with most of it burning up in the atmosphere. Some of the space junk did end up falling on Texas and New Mexico, though. And a school bus-sized piece came crashing down, albeit into the Atlantic Ocean. (Some people, of course, attributed this to god and or aliens.)